The process of growing tomatoes often involves strategic management of the plant’s structure to encourage the best possible harvest. Pruning and shaping the plant helps control its size and directs its resources efficiently, but topping is a specific, advanced technique used to redirect a tomato plant’s energy away from continued vertical growth. This practice signals the plant to stop producing new flowers and foliage, instead focusing all available sugars and nutrients toward ripening the fruit that is already set on the vine. Proper topping can be the difference between a late-season cluster of green tomatoes and a final, abundant harvest of fully ripened fruit.
The Difference Between Determinate and Indeterminate Plants
Understanding your tomato variety is the first step in deciding whether topping is appropriate. Tomato plants fall into two main categories. Determinate varieties, often called “bush” types, grow to a set, genetically determined height (typically three to five feet) and then stop growing on their own. These plants flower and set the majority of their fruit within a short, concentrated period, making them essentially “self-topping.”
Indeterminate varieties, by contrast, are “vining” plants that continue to grow, flower, and set fruit indefinitely until killed by frost or disease. This continuous growth means they can reach heights of ten feet or more and require consistent support and management. Topping applies almost exclusively to these vining, indeterminate types, as removing the growing tip of a determinate plant will stop its growth prematurely and severely limit its single harvest.
When and Why Topping is Necessary
Topping is done to redirect the plant’s energy. Indeterminate plants naturally prioritize vegetative growth, sending resources to the terminal buds to grow taller and produce new leaves and flowers. Removing the main growing tip eliminates the dominant growth point, causing the plant to allocate its energy to the existing developing fruit.
Timing this action is tied to the length of the growing season and the onset of cold weather. The ideal window for topping is four to six weeks before the date of your region’s first expected fall frost. This timeframe allows the plant enough time to mature and ripen its remaining fruit before the season ends.
Topping may also be necessary when the plant outgrows its support structure, such as reaching the top of a cage or trellis. Allowing the vine to flop over or cascade down can lead to broken stems, poor air circulation, and fruit susceptible to pests or soil-borne diseases. Cutting the top growth at a manageable height ensures the plant remains stable and accessible for harvesting.
Performing the Topping Cut
The topping process involves identifying and removing the main growing tip, or terminal bud, from the highest point of the vine. Begin by sterilizing your pruning shears or scissors with rubbing alcohol to prevent the transfer of plant pathogens.
Locate the highest cluster of fruit that has enough time to ripen before frost. The cut should be made on the main stem one to two leaf nodes directly above this last viable fruit cluster. This positioning ensures a few leaves remain above the fruit to provide shade and continue photosynthesis.
Remove any flowers or very small, newly forming fruit located above the chosen cut point, as these will not have enough time to mature. The goal is to focus the plant’s remaining resources solely on the established fruit. Carefully cut the stem cleanly just above a healthy leaf node, ensuring not to damage surrounding leaves or fruit trusses.
Managing New Growth After Topping
Once the terminal bud is removed, the plant’s hormonal balance shifts, resulting in the rapid growth of new side shoots, known as suckers, which emerge from the leaf axils below the cut. These suckers attempt to continue vertical growth.
To ensure successful energy redirection, continue removing these new suckers as they appear, especially those close to the top of the stem. If left unchecked, these side shoots will compete with the fruit for resources, defeating the purpose of the initial topping cut. Removing small suckers (typically less than half an inch) can often be done simply by pinching them off.
Allowing a few lower suckers to remain can be beneficial, as their leaves help protect existing fruit from sunscald, particularly in hot climates. Since the plant’s overall growth demands have decreased after topping, consider slightly reducing the frequency of watering and the application of nitrogen-heavy fertilizers. This final management step ensures the plant focuses fully on ripening the remaining fruit.